Food preparation systems are well known in the food science and consumer goods area. Such systems allow a consumer to prepare at home a given type of food, for instance a beverage such as a coffee-based beverage, e.g. an espresso or a brew-like coffee cup.
In the following description, the invention will described in relation to a its specific application to beverage preparation systems. However, the invention globally encompasses systems for non-beverage items preparation, such as for instance ice cream, soups comprising particles (herbs, croutons, etc.), jellies, dairy items (e.g. yogurts, cream desserts, etc.), or any kind of similar non liquid flowable edible products.
Today, most preparation systems for in-home food and beverage preparation comprise a machine having a so-called “brewing chamber” or “brewing unit” which can accommodate portioned ingredient for the preparation of the food or beverage. A so-called “brewing unit” comprises several parts which are designed to be assembled so as to create a closed cavity wherein the food or beverage ingredient can be placed. The brewing unit comprises means for injecting a preparation medium under pressure such as a fluid which is typically water through the ingredient, so as to prepare a corresponding food or beverage, which is then dispensed out of the brewing unit, to the consumer. The preparation fluid is sourced from a fluid conducting system of the machine to which the brewing unit is connected. The preparation is performed within the brewing unit at a pressure above the atmospheric pressure, which is typically comprised between 1 and 20 bar, preferably between 2 and 15 bar (relative pressure). The preparation can be performed by passing preparation fluid through the ingredient in a loose form or through the ingredient contained in a capsule or pod. For this reason, it is an essential characteristic of a brewing unit to be able to withstand a pressure difference between inside the cavity, and the ambient pressure (which is generally equal or substantially equivalent to atmospheric pressure) without opening itself when pressure inside the cavity increases (typically fluid pressure, e.g. water pressure).
Ingredient portions can be pre-dosed before they are placed into the cavity of the brewing unit, and can take the form of soft pods or pads, or sachets. More and more systems utilize semi-rigid or rigid portions such as rigid pods or capsules. In the following, it will be considered that the beverage machine of the invention is a beverage preparation machine working with a rigid or semi-rigid capsule, or with an ingredient in loose form such as roast and ground coffee grains, to be placed directly into the brewing unit of the machine.
As said above, the so-called “brewing unit” of a machine comprises a receptacle or cavity for accommodating said ingredient, that is for instance contained in a capsule, and a fluid injection system for injecting a fluid, preferably water, under pressure through said ingredient, for instance by piercing through a wall of the capsule that contains the ingredient. Water injected under pressure through the ingredient, for the preparation of a coffee beverage according to the present invention, is preferably hot, that is to say at a temperature above 70° C. However, in some particular instances, it might also be at ambient temperature, or even chilled. The pressure inside the brewing unit during extraction and/or dissolution of the ingredient is typically about 1 to about 8 bar for dissolution products and about 2 to about 12 bar for extraction of roast and ground coffee.
By definition, the brewing unit comprises means to conduct fluid through the ingredient (e.g. fluid injection means such as for instance a needle), and a “closed cavity”, that is to say a cavity that holds the ingredient within said brewing unit, such that said ingredient is not displaced out of said cavity under the effect of fluid passing there through, during the whole food or beverage preparation cycle, and until said ingredient is extracted or dissolved as a final food or beverage that is to be delivered to the consumer through a dispensing opening of said brewing unit. Preferably also, the so-called “closed” cavity of the brewing unit should ensure that no fluid injected therein escapes said brewing unit, except of course as final food or beverage that is to be delivered to the consumer.
In other words, a “brewing unit” comprises all functional elements necessary for holding the ingredient—be it loose, or contained in a capsule or pod—, and directing preparation fluid through and mixing it with said ingredient, during the preparation process and until final product delivery to the consumer. At all steps, the brewing unit resists the pressure difference between inside and outside of its cavity, such that:                fluid can only flow from its entry point into the cavity, through the ingredient, towards the beverage dispensing opening of the cavity,        and in case the ingredient is contained in a capsule or pod, the brewing unit encloses said capsule or pod so as to guarantee that fluid pressure increase therein does not damage the walls of said capsule or pod.        
In food and beverage preparation systems known today, the brewing unit is built-in with the machine. In some cases, for instance in some beverage preparation systems that function with capsules, one part of the whole brewing unit is detachable, which is often referred to as a “capsule holder”. However such capsule holders do not contain the ingredient completely. Such elements of a brewing unit which are detachable from the main machine base are convenient for the consumer because they provide a possibility to easily place the ingredient with said brewing unit.
Finally, in some known beverage preparation systems, a part of the brewing unit also contains fluid injection means for injecting fluid under pressure through the ingredient, for instance by injecting water under pressure within a closed capsule within which the ingredient is enclosed. Such a system is described for instance in European patent EP 1 688 072 B1, which strictly speaking, cannot be considered as a whole brewing unit, because although it encloses the ingredient (which is contained in a capsule), and also comprises the injection means for injecting the preparation fluid through said ingredient, it does not enclose the ingredient capsule sufficiently to guarantee that said capsule can resist an increase of pressure. In order to completely enclose the capsule, the system disclosed in EP 1688 072 B1 further comprises a plate that is part of the machine and cooperates with the detachable capsule holder to completely enclose the capsule when fluid is injected through the ingredient under pressure.
The detachable capsule holder disclosed in this patent is disadvantageous in that when it is disconnected from the main machine base, residual pressure within the ingredient (i.e. within the capsule that contains the ingredient) can push the two parts in the open configuration, and the remaining fluid can flow back and be spilled outside of the capsule. Unwanted opening of the brewing unit under the effect of internal pressure, leading to backflow and spillage, are of course undesirable for security reasons (in particular if the fluid is hot water), and obvious cleanliness reasons.
The PCT application WO 97/43937 discloses an adaptor for a pre-packaged coffee dose. The adaptor comprises two parts hinged to one another: a coffee dose holder, and a lid able to pivot around the hinge to close the dose holder. It further comprises a handle to place the adaptor onto a coffee machine. The holder and lid disclosed in this document can be conveniently fastened or unfastened by using the same hand that holds the whole adaptor. More precisely, this is performed by using a so-called “lid operating means”, which comprises a lock-pin of the lid that fits into a hollow of the coffee holder handle, jutting out laterally so as to allow operation of the lid by a finger of the same hand that holds the device.
The US patent application US 2011/0162533 discloses a coffee holding arm of a hand loading electric coffee machine. It comprises a lever, a container for holding a capsule, a capsule perforation device that is pivotally attached to the container such that when closed onto the latter, it pierces the capsule to allow coffee preparation. The attachment means for attaching the coffee holding arm to the coffee machine are placed on the container, such that when said coffee holding arm is secured functionally to the machine, the perforating device is located between the machine and the container and as a result the container and the perforating device cannot be disassembled.
It is therefore an objective of the present invention to provide a food or beverage preparation system comprising a fully detachable brewing unit able to obviate disadvantages of the known systems, and which can be cleaned completely separately from the rest of the machine.